SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38818319b74dde0de7740e0caf35f86c38924a5421a5ab8adde7d19ec04a83d7' 
  AND token = 'gKv1COwjvj7Kn+WbbAH5xX+epGRZQDqmGhaGBPZ+sbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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