SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abffcda64da08cb6fd2855f6240046503e18e3388ac1c799485f789f3f309fa9' 
  AND token = 'h0fMHuopQhmlr3NezQZGgKwFtqoT1Kyi+lFIMc1uAd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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