SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e301cec370d24d125827d608c02ae6ff46dc50eb73ba92d646b73c3dd298a04' 
  AND token = 'Na3xQDQnIsMIK1ZwbUZ537ZARWjBgASvXjGCyFb29yM=' 
  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"
    }
  }
}