SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6657c39b3552692d8930e005507cbd50b32d15ecbd5f0a613f24c1ab23b741a1' 
  AND token = 'xXaPw3P+mGtF+kArOfWQAa33KKT6Xbo3Xsu0tOnXQEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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