SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf3fb1ed5335ee4ed094733264bb67c84ba2906d4d0e2678ef354230162be176' 
  AND token = '48kbmUtQFLuFMsptxvtP1za0FVlIrrd6+F+loMxK48A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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