SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9eb13a22b55999fe4f913b57ba86d0c0d878f61d581da252c44de947a13c0bc9' 
  AND token = 'QBf7ZbK2xagC4mnB/1ceSbI6tajGzMHMD6YrLP93Bi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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