SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '681fb97bd69f554802a92ad56db3fb4804d176fc9db4dd33f0d0a57eec3149ec' 
  AND token = 'QxR+ii7ztPJEDb4BxsYsPHZ/Jyyl0nVQ3OA6rIFHRKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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