SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e743348add5d19758bde37fe7bd9fcfdedb4dac4d5c772161ec9d88df54d6375' 
  AND token = 'nm+/1UKtwh1Js98GNhAxbJDojovRgGSyyDL5rvGL9yo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}