SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6af291485c3916bfe04d0a46957e07fba9d51fb3a553094cfaaecb7b03972f24' 
  AND token = '4a8YtkHwlwKFdHsJ3WolPwVQFm6GH3MGNXGftTXL8BE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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