SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '903996dfbf416d6f2b5805b33b4e3a5da1645b584df124a219aa29a74a70747d' 
  AND token = 'tBT/DFCR/vBvqISmoEj6YMvGu2gbzCuhJ251ruLaApk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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