SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94aa862f57b9791234dc2ab988caaa1d23492d86a0a2a3721d1462717136df85' 
  AND token = '9wLVoGeuTFtd6adtslvbRgejYqJQ6FApJvLTjZC9+YA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}