SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49c85771a03aacee69042cf298e638f0a3f709e65ed07136593a51d6e6239cd0' 
  AND token = '8FfP64Sf/YeJCFTP60lvpCivLPz/ZImCmRmZ1GnoysU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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