SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a3b6bc4b50cd3f6f1dda63b2f691503160ae7a8825f5f313f383e44821db721' 
  AND token = 'TcZFJWYrzu/mno/J9jFvaAD5988j0IINgWS433FlOag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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