SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '356c4ca29b295c826479c6250968f4375e1a18ed34b87e7240f9c9fedf922a19' 
  AND token = 'VwJtMW2+6oxgZ6/gePYrObvA8+8NEGqIrQXl7frYSr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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