SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af4891263735401454f6bb62c1a6626e55f91c421dc1758a64c9cb706f83ff1c' 
  AND token = 'm4pxSpv0KO4pw9G6ETjcRl+//YYkMQ5HPAZ07YkldVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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