SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '646ac2640bd521969cb8d506e9a359cf6b01ec2042323edffc1ba5c1f234943f' 
  AND token = 'CJp5+RI6eR1Y0oiE2KNb+1PzIwLaGQLZZwMdhvplEu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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