SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77add27691b53871875b33d9d95b076857f45535fcb931e18195519c0eab1161' 
  AND token = 'dU8XWoVtgiOj+Ju/q048MnEJFk9feSJwRZfEIlnoM0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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