SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4972fcb846bf2d934d780693aead75a75328f7acb6d4237e2fc64b592eefd530' 
  AND token = 'bsEw06h9E3NXVuGf3mMyBhcf5bHwZ+JBzWVXBA4KtPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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