SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5cbfc586897c66bd8d9abc2f5c7aa162853d2bda40f58af875d4d8d32d8441d' 
  AND token = 'lKIunVIum+IXEslfPGGadB738qzbMWvtrjYgOi9uOMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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