SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '475af61ac448af7c4d109899ddd397bf70478f3e4892898945545d0b0e4c6cfb' 
  AND token = 'HDg2RQr77v8loaB6ZuJIkzUdWUekPHHb1+7TvP9eAa0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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