SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c112a670ee679d9c47355ed7092beefba9cdf43e88db3623307c869fe7a32671' 
  AND token = 'atoGfNu6X88uNwhbAKw+zqcA3tFnuYmzuJxiCZ3Qp54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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