SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad3cb7e0fc4a867d24e825aac2b318d669b1749f2315f49cbecd3acbb617141d' 
  AND token = 'aAqZadfYPKIwwmT8ji5xL/XgtM5LbvsR/vD8OP2gMNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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