SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc9334f974b6f3467cbf15e5530b61ed537a3083e9611ea78f9de78fe2b695f9' 
  AND token = 'KAklbnEtKNT3cV3/FYx6GB2dz1PgAmNj+4BpYhaWgIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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