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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0f0e811740c4799aa897215359f5cdcbf69319af6089dc38f6feac3f7f14281' 
  AND token = '71PzK/XR8e5ekHjhhj+mu0dUOaemQr/woKYsfZjha9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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