SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af214f608d9596b3ad21106608b892271ac4bee45c8af0e864dc95cef469d9f3' 
  AND token = '2vvlfFIft0dlLXE/aFnbWX2tVDtupozuh5tsts/twHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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