SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b370c916670c78ad65c4f123c2a60547968d7e7c908c73eceda7238a4cc1ab23' 
  AND token = 'wAclShB48Ebs58lYDu2dho+jxG1nAImcUhfv+p1Vc38=' 
  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"
    }
  }
}