SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f50d0c20f1669706788987d0ee71cc322464c80eb8c1afaadfc5c0144b17253' 
  AND token = 'i+Zb8Hliiqnh/eQ5+hxyE60v3XllXZYLRVi9mwlLzuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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