SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81263e88751bec6787e22a307a561732969b5c389f7c883ccd66c3400e37ede5' 
  AND token = '45py8mN9xEaM4upLO7c0h0IlBqfcCAytTlRYJlKpZaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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