SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '347ab9d65bd6494b0fbbaec4fed919166e0ef7f9dd92be8f88fd80066acd90ce' 
  AND token = 'pUS3tbRQ7YCaIFLbW2VuGJ6LpgWKe0Zqqnnu5nV2TW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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