SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec64b8d09ff8548174c6d3a4f887ffe009e44b646884dee8e70d0ec39fadca81' 
  AND token = 'MTkWk2GbdwzRgsYFZ38052wILBYA6eU9BTLhP2s5UeU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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