SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd64b53d8cd7c3b2bed287185fc06499eedd4eb69dd9281b5ddf6b71bce229c0a' 
  AND token = 'l/E5iCcw1IMsB0h41Qh1Hv/Ok2z9W16yOTnpSA7fLKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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