SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e66258a547c9a28e5f938b3bcc8708ddb6e48cf4cc097beae2a2db870de843a' 
  AND token = '42oYkZxVqH9uAcD8XYDLCVbkBrR+Urac5uxlOXJFCTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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