SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '766e1779025ade889fadee4230224c1136ea043634206e37beab575af1588279' 
  AND token = 'bdhDvB8T9bYKPNIgcXgspA0xj+PzxJLAr1S7RTFiMgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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