SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3424b4680c7dd52aad04f8060b1cf4e20ec927373c5d89dc163543388e634eb4' 
  AND token = 'OvKf9VIlRCVGODRB/IapOSc11E6CTdjizgXTpYTkOeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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