SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'debdc6b4d7a192718d73396b2ca316df03154c2b11b39aefcae882b8e0f715cd' 
  AND token = 'JKYWWl+gAffk065t+T/Dk9ffgXS8JWdOi614SMwJbiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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