SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd27c853b7f206007f448c2a8584c795083a4533200999fbfd2fde7312c79cf80' 
  AND token = 'QqmWx6dtJtTptorRlWOLVPWBsqJQVmvI/BdPMZDSGuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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