SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7a658a5334942b3371222828a89dbecf4516e4bd106c4a5ebcc722d9433bd61' 
  AND token = '+Njs34sGmnKqimeWxLFxtFYzO3aZH5fsjhs/EByzGV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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