SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90dd1e5775481008556296ebbb97564fea27b65eea3237f420ce3c3dc9df88f6' 
  AND token = 'kOhK2q3ocbwXTTmMrbwuEk87vplJnDeCSPi41K8kCw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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