SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '977b4b63c299a847be597639a634328ed1e305ee5374954b8dfb5a2678524a45' 
  AND token = 'e7HL5FPmC9OzEa7qcrXRRv1NSi7AuwarM0GFLoHssms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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