SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c7df3d454cf4332d93b438c33d1d2a402f33b32175211396bf07f00ce5fe7b2' 
  AND token = '6FY2afkx/ghC/5b2PMPVpqGB+UsseuftjRVh9nYjg38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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