SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57933d2c3fb82c0d9cc180476a8b11f07806133452c6adee4894cf98cdb0f07d' 
  AND token = '02hJyHDv3kwYC8VnBgnkxmTrVsXwhtaZXbFy+Xj6hnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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