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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d6844d3bf21c3163d9a7df2b0d49c69aad34a1e2c5ec7a212fbf81053f80e93' 
  AND token = 'Q+rfxbNlQDdOa8LY/Hi7wB6/JkT76kD+xYQ0Aj7Yiq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}