SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b064487794ba84f9a74de02cca278977eddf018495afd9cade07cb23d28a0cc' 
  AND token = 'z0Z7Y2eHMHIWgz5bpbZy+Wwa34HESPAAo4VQJqNbat4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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