SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0747c6d297940a54aad77306772f3104e9a3b8363baf47d479bd3718c8f63ce' 
  AND token = 'uXEl9aiW2EguaB/39vnAT9mbEjTwjDKgh5utWweb+Ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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