SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ad945687fc745c5456129d573dd289c8f27cc231dd0a9fe5beb57be875384e4' 
  AND token = '2tpBDpRDixqGLDzdulMquGVBLNb+y5VhKVzqGlsd19Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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