SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b66ace2c831c6914e6fe930a2faab0ac123f36f889c01272602357eb8193cba3' 
  AND token = 'u/7uqELVdjjRuIwX7GNsG1nvm26/bgN29BbVuVHduP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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