SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21d6b44303a21f3f51b5218cca2b0a04a617aed257aff9183554ab932e964134' 
  AND token = 'cVl+yuNXer/CbPxoEkSBD7WKdBJVspo7ilSzgojY5ew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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