SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb9bc6dc8c1acec890fa52acd81d7705c902a293f7fe2212d210de4cc2df3d9d' 
  AND token = '+AHZ6wLwJKqOzWyGbzCo+Zl+7h/JHwl4Yq+Dl8duzoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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