SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e403ad2508cdc39531e19ffaa918329cd5ebdc93a643888490f8654d0e8438e' 
  AND token = 'F6XI5MbgrNSX53mn6Esw6F+iwCSTZcH36134tKbHQ9Y=' 
  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"
    }
  }
}