SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6dbddaedea0bea549935bc28214b8dea7dd4b59a2664e349bd5159aec804266' 
  AND token = 'WlJYCsVrKhIx8Kbw3/Spq9qfHpU4YefbXLWpr98D9l4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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