SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f2fe993b252cef31f54194316258855c38207a9f6add5267270881d0fa142b0' 
  AND token = 'mfsVjiVdLDrGpTMtGCgXUDo5+q9lmpQAGndNmvJlJIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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