SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8a4856a0ec74fb95308e3061dbf8bbab7d1b1f633500f25bd7fec625c083830' 
  AND token = 'kxqwFrCMlyFIJFFPRJ/pqfwpODpMJvhn4Rboiuhi0Io=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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