SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '439ae0cf895fc4c8bdd2539e0a05e97e092610971df6b066d9b23e2615e2466e' 
  AND token = 'rs5SmRyMiEPSVnFXfkdva7yLjanY8WwvNhn5mMA/QvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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