SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a0ef28c2c096478c86d781981fd3aa584bf85f0a419fc6a44a9c5cf83a815da' 
  AND token = '+OqmdyBqyOFbIubildq0utvNMipXZOjsKjftw1PLnoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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