SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53a553f2a549aa850249575e52c37a7a20a90cb7ce6bb37d4ef42172ba4a68bf' 
  AND token = '+QeRSKRkQCiDoeV/j4iaX+GebQx7PFUbhmcwE0OMkJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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