SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6936c86ff5e21da9bc36b2dd857a846896a93a718dce16640b891f6814c98d50' 
  AND token = '4hiGHdHZlnwcc5BB272A0rVPNQ+Vx0jLWYD7/vBG5J4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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