SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef8ba3e3425a3e51c029ef4394465561e65b39429bdc6cddaee4b2725bfa2fc9' 
  AND token = '1gn7D8RekppJt3CUSixWIxbNjGw95k1aVhHGRI+GOKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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