SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76e69292edfd008583c91cb67cc299f4088f2347f606387e7aaf4b2171ca3303' 
  AND token = '57dc6kwZ/dLItfYgHTNL4Ot3iEjx0q3Bei/uL6dL5m4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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