SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '426d21a50835975678d9481a0ed43228c17533c6d10883095c9d09d37e482869' 
  AND token = 'ZCRbIvkLj0O8qZxVcAfwShO+sNs4aL518xFhm613n48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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