SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bdf6a39c81e97c2bc425365eb8dc202d2a80f3dc0cc76affa1c424024468cd0' 
  AND token = 'S5qpkwg2uxKwB5UbUmJQDiJF/P5jMrL33+jVYntFc3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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