SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf51784751cb4eeba89cd99841d696eb5ce3d508889252574e78be31f7f11ab2' 
  AND token = 'fKrmj1hukVZProCOUFPWSOFDrhMSnNnk+XnLVJ/v9Yc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00077

JSON explain

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