SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2a7948c7cf4b00cdf12b954e0f72ede0ec4c0b4791d60cb173b8ab13f15ff54' 
  AND token = 'tAc+dfj6wws0BkWoKVDXp/TKB7/YFQJQogc8H1kxzUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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