SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '943758a4fa1f445b8f01d4299064d8250c4f36013425263f7b58bdaddc31ec6d' 
  AND token = 'zzPDBQii4yABenkzJU8IXCwPb5wj2psH5fYR8potugM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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