SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '558ed8b32ea16527f8d8a68e57681948bf1ee4b5e15a14c6bcd527af7e473258' 
  AND token = 'QbjYTkYU+UfmY/AkPAB1fBp+joD68+jqjDC9D1ZMI/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}