SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '960f0d8aa39b6cab853e3bb36760db012387be33dea9362ee5d5734a805346a0' 
  AND token = '+Zl6DKdTZK7+Yk+wOJ5YXieEejdnWJ+cXZgolr6bDRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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