SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '876a865cc4729a35c268969f8a41ce276474859b1476d63b0e65bf9cf2e68d29' 
  AND token = 'dKhPf06pLNzvpN9NkGPySiVMwah7thTi7Qo2YbbAiFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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