SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4257816505089e4a40801ffc19f08d7ac5f56ffbc16dc7748a314fe52f091e72' 
  AND token = '8qPSNV8wzMA+RiTIYjQLslvVVt/umnsBKVIqJoxh6c4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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