SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38cb0835056be75a4008e4cc943ad2e683961215b7e0a03d756c8b926da0bab2' 
  AND token = 'QGUr0zTbB0nlZZjaeOYlERtRVsCLxMeXICZ+ZAa6ka4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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