SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2e866cc6377161ce47861e35d264af4251afdc4275fadfc35842558e7de77c3' 
  AND token = 'wG06kP29uojEE1hYZHeS4PLss/RCrtveeDrYhDgHjHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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