SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bf835823f510ab16aeed3a77f2098c10d116e13eb26266029e244cbf5a99c3a' 
  AND token = 'hhQHPFEQt5RPEQgUCk1WmhvVKzBUH2y9p/Rz/0RkWnw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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