SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d8e5f619685c35bec22743228ef2a23addafe6b5ba21827a4faa359d63f90e9' 
  AND token = 'w23QgqrwtBwBOLY24w2UFtQff54djDlNINwOFzWOezQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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