SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0f806ba868c9a3213957679dc4e0e5285e465eae7d7d6b84b4e8296266bc6b2' 
  AND token = 'zgDWLWVDkujUzjqjBLoat+tnQCMxCA/JKC+S+Q++u50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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