SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '908ad72a24bdd51bdde71dee85026ea35d0dae28992ea69f7b0ae6e0668f8fe2' 
  AND token = '5dew9xxyqb26nVDyToIAPx/cCnNAWKq2PLq/G82J7zc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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