SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9796747eba94a535c871cfdae4ab394ca58787ca5d9364a3128796a187cbed4b' 
  AND token = 's7sREFTjD5LrxUdLrQM6iR4B+zrUmKJs9biNFmMYxPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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