SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4e0f7956c3faab55dfebd6f58016aface20a37ec80e13dbb6fa89465401f497' 
  AND token = 'Kw2uYJltORCyIGdm+BaHddFpkrjzcMSWuqZ7pCBEAg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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