SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21dc718c8416aec2842a023eaa4210b6c66b9fae5e0140fcffad240828208c00' 
  AND token = '5eoDwboLcU8R7nw7cZuACAcor7MZISB/J3Yn9ACXaN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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