SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad9db93b62ccee98a47ce53c7615aca480eb046ced4454cac78693ea86c34532' 
  AND token = 'c5ZiVlCd22WZAYaH76amwAGRgrHwzH6Bhyv9rgYeFZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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