SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4c7ea8352fdae5d85bff030fe6eebb3b58ca601039ff6a54881cadaa6da6979' 
  AND token = 'cJ53CNlphzT4bKElub1VjOnaq7PFK2VJ0VoOgPYwmXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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