SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcd0b76bc11827a7f53890749f99c9fd363168917ea726d02f2346018fb61bb8' 
  AND token = 'kjwi+5BN5qnjYfchE87XMza85vwDkfWGP072lZjxp/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}